Blue jeans have an inseparable one-way word association, and what makes that so interesting is that blue jeans start out yellow – well, sort of.

When “jeans” are brought up with no other descriptor, the assumption is that a person is talking about comfortable blue pants. Jeans are warm, durable, relaxed, and cut in a variety of perfect fits. To top it off, their blue coloring seems to coordinate with pretty much any other color.

The jeans we wear today are the result of amazing evolutions in textile production and dye process. The history of jeans begins in Genoa, Italy and Nimes, France several centuries ago. These two locations, where the woven material was primarily produced and mastered, are where we get the terms jeans, from Genoa and denim, de Nimes.

Both places produced heavy cotton blends called fustian, and they used a durable diagonal weave style called twill. The twill woven cotton was ideal for working class and common people of the time since the material was relatively affordable, comfortable (jeans being the more comfortable of the two), and held up in more laborious settings.

By the mid-16th century, Genoa began having more success in exporting their fustian fabric to England, and later the American Colonies.

The color blue and its association to jeans is another element to the history, and one where some science is involved. Blue coloring can come from a number of dyestuffs, but indigo for textile dyeing offered many benefits.

Since ancient times, indigo dye has been preferred for its overall color fastness – its resistance to fading over multiple washes and exposure to light. The trouble with indigo is that it is not water-soluble, which means it will not naturally dye the intended fiber. This characteristic and its overall dye process makes indigo fall under the category of vat dye.

In order to make vat dyes work, dipped material must go through a reduction and oxidation stage, sometimes a series of them. During reduction, indigo dye is converted to its yellowish-green, water-soluble leuco-indigo form when in an alkaline solution with reducing agents. It is during this process that jeans start out yellow (or the yarn fibers do, depending on manufacturing process). After dipping, the fiber goes through oxidation, usually by air, which returns indigo to its fixed, water-insoluble blue. Multiple dips help increase the brilliance and darkness of the blue dye.

Another factor greatly contributing to color output is the pH of the dye bath. Vat dyes work well in alkaline conditions where fiber better absorbs the dye. For cotton blends, a pH of 11.5-12 is ideal for color absorption. In fact, pH has been such an important element in dyeing, that efforts to optimize the process have been introduced over the years. Something as simple as introducing fiber to the dye bath could change the overall pH of the solution just enough to decrease the efficiency of the dye. To stay within a narrow pH range, buffers, bases or acids enable a more effective dye process.

By the 19th century, the millennia of dye perfection and the centuries of textile perfection met at a perfect time in American history when gold prospectors were heading west and industrial production was in a golden age. It is during this time where Levi Strauss, a Bavarian immigrant, moved from New York to San Francisco to open a dry goods business. He catered to customers who not only needed dry goods, but also durable supplies, including good working clothes. In 1872, Strauss was approached by Jacob Davis, a tailor from Reno, Nev. Davis introduced a way of making jean pants that were more durable due to his design involving rivets around strain points of the pants. Strauss and Davis partnered together, patenting the design and marketing the pants. At the time, Levi jean pants came in two color options: cotton duck (like canvas), and blue denim.

How blue outlived the cotton duck goes right back to the science of indigo dye. Each wash would strip away tiny amounts of the indigo dye. But because the dye had tightly bonded to the fiber, each wash also meant that little threads of the cloth were stripped with it. Every wash softened the material, making it more and more comfortable. The fading quality of the indigo dye contributed to a rugged look and an unwritten personal story. By 1911, Strauss phased out the duck color and ran only with blue.

Blue jeans began to symbolize ideals of the American West. By the 1950s, partly thanks to Hollywood, jeans became associated with rebellion, youth and freedom. Since then, jeans have become one of the most common, universal garment.

The history and science behind blue jeans goes way deeper than this overview. A great read is “The Master of the Blue Jeans,” a book that explores an unnamed artist of the late 17th century. The artist is dubbed the Master of Blue Jeans because many subjects are depicted wearing garments made of blue denim.


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Karen Martin
GoldBio Marketing Director

"To understand the universe is to understand math." My 8th grade
math teacher's quote meant nothing to me at the time. Then came
college, and the revelation that the adults in my past were right all
along. But since math feels less tangible, I fell for biology and have
found pure happiness behind my desk at GoldBio, learning, writing
and loving everything science.

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